Motor-control system



Forward Sfop Reverse l6 WITNESSES:

i I INVENTOR W Ado/ph A. Gaza/a.

Patented Sept. 28, 1920.

PATENT OFFICE.

ADOLPH A. GAZDA, 0F WILKINSBURG, PENNSYLVANIA, ASSIGNOR TO WESTINGHOUSE ELECTRIC AND MANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA.

UNITED, STATES MOTOR-CONTROL sYsrmvI.

. Specification of Letters Patent. l atented S t. 28 1920 Application filed September 30, 1916. Serial No. 123,068.

To all whom it may concern:

Be it known that I, An'oLrH A. GAZDA, a citizen of the United States, and a resident of 'lVilkinsburg, in thecounty of Allegheny and State of Pennsylvania, have invented a new and useful Improvement in Motor- Control Systems, of which the following is a specification. 7 My invention relates, to motor-control systems, andparticularly to'such systems as are employed inconnection with planer-s or similar machines requiring frequent stops and reversals of the driving mechanism.

My invention has for its object to provide a simple andefiicient means for controlling the circuits of electric motors whereby they may be quickly brought to rest and automatically accelerated for operation in the opposite direction. V

r A control system arranged in accordance with myinvention comprises an electromagnetically operable switch that is controlled in accordance with the counter-electromotive force of an electric motor to complete a shunt circuit for the starting resistor of the motor. The motor .circuit is controlled by two electromagnetically operable line switches which are provided with back contact members for completing a dynamic braking circuit for the motor when the switches are opened. The line switchesare electrically interlocked in such manner that it is impossible to close one of them when the other occupies its closed position. 7

It is desirable that the switch for controlling the startingresistor be opened before the line switch corresponding to the direction of rotation of the motor is opened. This result is' accomplished by the electrical interlocking of the switches mentioned above in such manner that the opening of the switch for controlling the starting resistor effects the opening of the line switch that is closed. p My invention will .be described in connection with the accompanying drawing in which the single figure is a diagrammatic view of'circuits andapparatus embodying my invention. I

Line conductors 1 and 2, whichmay be connected .to any suitable sourceof direct current, supply energy to an electric. motor having an armature winding 3 and a shunt field-nmgnet winding 4. A starting resistor 5, which is in series with the motor,;1s com trolled by an electromagnetically operable switch 6 which has an actuating coil 7 that is connected across the terminals of the motor. A relay 8, which is mechanically connected to the switch 6, is respectively opened and closed when the switch 6 occupies similar positions. x

The main circuit of the motor is completed for rotation in opposite directions by line switches 9 and 10 that are respectively provided with actuating coils 11 and 12. The switches 9 and 10 are mechanically connected to relays 13 and 14, respectively, which are opened and closed when the respective switches occupy their corresponding positions. The operation of the motor is controlled by push buttons 15, 16 and 17 which produce effects that are indicated by suitable legends placed adjacent to the switches.

It may be assumed that the motor is stationary and that the various switches occupy their respective illustrated or inoperative positions. To start the motor in the forward direction, the push button 15 is actuated to complete a circuit which extends from line conductor 1 through actuating coil 11, push button 15 and back contact members of switch 10 to line conductor 2. p The coil 11 is energized to close switch 9 and thus complete the main circuit of the motor for operation in the forward direction. This circuit extends from line conductor 1 through switch 9, armature-3, starting resistor 5 and back contact members of switch 10 to line conductor 2. When the speed of the motor is such that its counterelectromotive force reaches a predetermined value, the coil 7 is energized to close switch 6 and thus complete a shunt circuit for the starting resistor 5 to furthervaccelerate the motor.

The closing of relay '8 establishes a holding circuit for the coil 11 which comprises relays 13 and 8. The push button 15 may be released at any time after the closing of I the switch 6. The switch 10 cannot be closed by the actuation of the push button switch 16, by reason of the fact that the switch 9, in closing, creates a gap in the circuit of the push-button 16, traced below, at the back contact members "of the switch 9. Independently of this circumstance, however, it would be impossible toefiect the closing of the switch 10 when the switch 9 is closed for the reason that theclosing of the switch 9 establishes a short circuit for the push-button 16 and the coil 12 which extends from oneterminal of the switch 9, through the conductor 18, the coil 12 and the push-button 16 to the other terminal of the switch 9.

To stop the motor, the push button switchv '17 is actuated to open the circuit of coil 7.

The switch 6 then opens to insert the resistor in series with the motor armature. opening of relay 8 breaks the c1rcu1t of actuating coil 11 and the switch 9 opens the main circuit of-the motor.

The opening of switch 9 operates to establish a dynamic braking circuit for the motor which extends from one terminal of the motor armature throughthe back contact members or switch 9, back contact members 'of'switch 10 and resistor 5 to the other terminal of the motor armature; The motor is thusqu'ickly brought to rest: 7

To start the motor in the reverse dlrecs tion, the push button switch 16 is'closed'to I which extends Complete. a circuit for theactuating coil 12 from line conductor 1 through actuating coil 12, push button switch '16 and back contact members of switch 9 to line conductor 2. The switch 10 closes to complete the main circuit of the motor for operation in the reverse direction.

c 12 is established by'the relay8 upon the closing of switch 6. The relay 8 thus controls the position of switch 10 and it is impossible for the'latter tobe'open'ed before thefswitch 6 has opened to insert there sister 5 in clrcuitwith' the motor'armature.

f to close switch-9 because the circuit, above traced, "of the push=button 15 1s open at the When the switch 10 is in its closed position,the"push button switch 15 is ineffective back contact membersoi the switch 10.

, Even ifjthi's were not so, however, it would itsactuating coil 11 and the push-button not be possible to closethe switch 9' because switch 15 become shew-erected upon the closing of the switch 10, as may be seen by tracing thecircuit from oneterininal of the I switch" 10, in its closed position, through the actuating coil 11 and the'pu'sh-button switch 15', to theother terminal. 7 p 7 V 'I'n' the arrangement described above, an electricmotor may be caused to operate in either directionupon the closing "of the correspondingcontrol switch, The closing of one line switcher-reversing switch automatically prevents the closing of the other switch; The line switches are so interlocked with anaccelerating switch that the" several The I gized.

switches must open in a predetermined sequence While I have shownfand described my in vention as embodying a plurality ofpuslr buttons .for controlling the circuits of the motor, it will be obvious that any other suitable form of controlling device may be's ubstituted therefor. Such changes may be made without departing'from the spirit of my invention as fall Within the scope of the appended claims. V I claim as my invention 1 1. In a motor-control system, the combina-' tion with an electric motor, of a switch adapted to be closed to start said motor and having an actuating Z coil, an accelerating switch,- means for tem orarily" closing the circuit of said coil,and means ope-ratively connected to said accelerating switch for maintaining the circuit of saidcoil ener .2.- In a motor-controljsystem,the combination with an electric motor, a pair of reversing switches and an accelerating-switch therefor,- and actuating coils for said switches, of relays operatively connected to said switches for completing a holdingqcir 'cuit for-the'aetuating coil ofo'neofrsaid reversing switches upon the, closing of the lat- .ter and of said accelerating switch 3. Inamotor-control'system, the combinw tion-w'ith electric motor, a pair of revers ing switches and an accelerating switch therefor, and actuating coils for said switches, of relays operatively connected to said switches for completing a holding cir c-u-it for the actuating -co1lof"one]of said reversing Switches upon the closlng of the latter and of said accelerating switch, and insane for eflecti-ng he 'OPGIIIIIg Q'f said 7 celer'ating switch to open said holding '01).-

cuit.

4. 111 a motor-control system, the combi; V

nation with an electric motor and apair. of

reversing switches therefor h'a'v'ing' actuating coils, of an accelerating switch, means for energizing said coils, and an interlocking switches, the interlocking' devices connected to s'aldia'cceleratlng switch and to oneof said i deviceoperatively connected to each of said reversing switchesbeing series connected in circuit with the coil o'f said one reversing V 5. In a motor-controlsystem, the combir nat on with an electric motor, .a pa r of-reverslng swltchesand an accelerating switch,

. of controlling means for efl'ectingthe closing of said reversing switches an'dimeans conshunti'ngpsaid controlling means" andf for malnta nlngrthe clostir'eof one of said reversingswltches', sa d means controlledby said. accelerating'switch causing the opening of said reversing switch when said accelerat 111g. witch is top-em "switch tom-aintainsaid'ccfl energized; a

trolled by said accelerating switch for 6. In a motor-control system, the combination with an electric motor, a pair of reversing switches and an accelerating switch, of controlling means for effecting the closing of said reversing switches and means connected to said accelerating switch for creating a short-circuit for said controlling means and for maintaining the closure of one of said reversing switches until said accelerating switch is open.

In testimony whereof, I have hereunto subscribed my name this 26th day of Sept.

ADOLPH A. GAZDA. 

